Sheet molding compound manufacturing method and sheet molding compound manufacturing device

Abstract

To provide useful improvements in a technology of manufacturing CF-SMC with a pin roller device.SOLUTION: A manufacturing method for a sheet molding compound includes: (i) depositing a carbon fiber mat on a running carrier film while dispersing, by a pin roller device, short carbon fiber bundles by dropping the short carbon fiber bundles; (ii) obtaining a resin impregnated carbon fiber mat by impregnating the carbon fiber mat with a thermosetting resin composition; and (iii) inspecting, by a magnetic sensor type metal detector, the resin impregnated carbon fiber mat for presence of any metallic foreign matter. The pin roller device includes rotationally driven pin rollers. The pin roller comprises a cylinder and a plurality of pins arranged on its circumference, and the plurality of pins are made of a magnetic metal.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates primarily to a method for producing sheet molding compounds (SMCs), and in particular to a method for producing CF-SMCs, which are SMCs using carbon fibers (CFs). The present invention can also be suitably used in the production of CF-SMCs. RuS Regarding MC manufacturing equipment. [Background technology]

[0002] CF-SMC is a type of carbon fiber prepreg, and has a structure in which a carbon fiber mat made of short carbon fiber bundles is impregnated with a thermosetting resin composition. In the production of SMC, it has been proposed to use a fiber dispersion booth having a dispersion roll for dispersing the reinforcing fiber bundles falling from above and a straightening plate perpendicular to the rotation axis of the dispersion roll (Patent Document 1). In a method for producing CF-SMC, it has been proposed to provide a step of inspecting the produced CF-SMC for the presence or absence of metallic foreign matter using a magnetic sensor-type metal detection method (Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 010084 [Patent Document 2] International Publication No. 2020 / 246447 Summary of the Invention [Problem to be solved by the invention]

[0004] The primary object of the present invention is to provide a useful improvement in the technology of manufacturing CF-SMC using a pin roller apparatus. In this specification, problems that can be solved by each embodiment of the present invention may be explicitly or implicitly disclosed. [Means for solving the problem]

[0005] Preferred embodiments of the present invention include, but are not limited to, the following. [1] A method for producing a sheet molding compound, comprising: (i) dropping short carbon fiber bundles onto a moving carrier film while dispersing them with a pin roller device, and depositing a carbon fiber mat on the carrier film; (ii) impregnating the carbon fiber mat with a thermosetting resin composition to obtain a resin-impregnated carbon fiber mat; and (iii) inspecting the resin-impregnated carbon fiber mat for the presence or absence of metal foreign matter with a magnetic sensor-type metal detector, wherein the pin roller device is provided with a rotatably driven pin roll, the pin roll consisting of a cylinder and a plurality of pins arranged on its circumferential surface, and the plurality of pins are made of a magnetic metal. [2] The manufacturing method according to [1], further comprising cutting the continuous carbon fiber bundle into the short carbon fiber bundles with a chopper installed above the pin roller device. [3] The manufacturing method described in [1] or [2], wherein the pin roller device includes a first pin roll and a second pin roll arranged side by side as the pin roll. [4] The manufacturing method described in [3], wherein the first pin roll is rotationally driven so that pins move from top to bottom on the side facing the second pin roll, and the second pin roll is rotationally driven so that pins move from top to bottom on the side facing the first pin roll. [5] The manufacturing method described in [3] or [4], wherein the sum of the maximum radius of the first pin roll and the maximum radius of the second pin roll is greater than the distance between the rotation axes of the first pin roll and the second pin roll. [6] The manufacturing method described in any one of [3] to [5], wherein the radius of the cylinder of each of the first pin roll and the second pin roll is equal to or greater than half of the maximum radius. [7] The manufacturing method described in any one of [3] to [6], wherein the peripheral speed at the tips of the pins of the first pin roll is equal to the peripheral speed at the tips of the pins of the second pin roll. [8] A pin roller device comprising a rotationally driven pin roll, the pin roll consisting of a cylinder and a number of pins arranged on its circumferential surface, the number of pins being made of a magnetic metal. [9] The pin roller device described in [8], comprising a first pin roll and a second pin roll arranged side by side as the pin rolls.

[10] The pin roller device described in [9], wherein the sum of the maximum radius of the first pin roll and the maximum radius of the second pin roll is greater than the distance between the rotation axes of the first pin roll and the second pin roll.

[11] The pin roller device described in [9] or

[10] , wherein the radius of the cylinder in each of the first pin roll and the second pin roll is equal to or greater than half of the maximum radius.

[12] A fiber mat depositing device comprising the pin roller device according to any one of [8] to

[11] .

[13] The fiber mat depositing apparatus according to

[12] , further comprising a chopper disposed above the pin roller device.

[14] An apparatus for manufacturing a sheet molding compound, comprising the fiber mat depositing apparatus according to

[12] or

[13] and a magnetic sensor type metal detector.

[15] The sheet molding compound manufacturing apparatus according to

[14] , further comprising two coaters and an impregnation machine. Effect of the Invention

[0006] Beneficial improvements are provided with respect to the manufacturing techniques for CF-SMC using a pin roller apparatus. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of an SMC manufacturing apparatus. [Diagram 2] FIG. 2 is a schematic diagram of a fiber mat deposition apparatus. [Diagram 3] FIG. 3 is a schematic diagram of a pin roll that the pin roller device may include. [Figure 4] FIG. 4 is a schematic diagram showing examples of the shapes of pins that the pin roll may have. [Diagram 5] FIG. 5 is a schematic diagram showing the positional relationship between two pin rolls that the pin roller device may include. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] One embodiment of the present invention relates to a method for producing a CF-SMC, which includes the following steps (i) to (iii): (i) Short carbon fiber bundles are dispersed by a pin roller device and dropped onto a running carrier film to deposit a carbon fiber mat on the carrier film. (ii) impregnating the carbon fiber mat with a thermosetting resin composition to obtain a resin-impregnated carbon fiber mat. (iii) Inspecting the resin-impregnated carbon fiber mat for the presence or absence of metallic foreign matter using a magnetic sensor type metal detector.

[0009] FIG. 1 shows a conceptual diagram of an SMC production apparatus that can be preferably used when producing a CF-SMC using the above-described production method according to the embodiment. Referring to FIG. 1, an SMC manufacturing apparatus 100 includes a first coater 110, a second coater 120, a fiber mat depositing device 130, an impregnating device 140, and a magnetic sensor-based metal detector 150. 2, the fiber mat deposition device 130 is disposed above the running path of the first carrier film 41, and includes a chopper 160, a shooter 170, and a pin roller device 180. The width direction of the first carrier film 41 while it is running is horizontal.

[0010] The chopper 160 is of a type that is also used in conventional SMC manufacturing equipment, and includes a cutter roll 161 , a receiving roll (rubber roll) 162 , and a guide roll 163 . The rotation axes of the cutter roll 161, the receiving roll 162, and the guide roll 163 are all parallel to the direction T. The direction T refers to a direction that is horizontal and perpendicular to the direction M. The direction M refers to a direction parallel to the running direction of the first carrier film 41.

[0011] The shooter 170 is installed below the chopper 160, and a pin roller device 180 is disposed below the shooter 170. The installation of the shooter 170 may be omitted. The pin roller device 180 includes a pair of pin rolls, that is, a first pin roll 181 and a second pin roll 182, each of which has a rotation axis parallel to the T direction. The first pin roll 181 and the second pin roll 182 are arranged side by side. 2, pin roller device 180 includes housing 183, in which pin rolls are disposed. Housing 183 has walls surrounding the two pin rolls and a roof with an opening for connection with the shooter.

[0012] As shown in FIG. 3, the first pin roll 181 has a cylinder 181a and a plurality of pins 181b arranged on the circumferential surface of the cylinder 181a. Cylinder 181a is rigid and is preferably made of metal (including metal alloys). The diameter of the cylinder 181a is not limited, but may be, for example, 60 mm to 150 mm.

[0013] The pin 181b is a rigid body, and is made of a magnetic metal (including an alloy). The magnetic metal is not limited to, but is preferably, for example, steel or magnetic stainless steel. Among the various stainless steels, austenitic stainless steels, which belong to the chromium-nickel stainless steel group (a representative steel type is 18Cr-8Ni stainless steel such as SUS304 of the Japanese Industrial Standards), are not magnetic. On the other hand, austenitic-ferritic stainless steels (representative steel types are SUS329J1 and SUS329J4L of the Japanese Industrial Standards) belonging to the chromium-nickel stainless steels, ferritic stainless steels (representative steel types are 18Cr stainless steels such as SUS430 of the Japanese Industrial Standards) belonging to the chromium stainless steels, martensitic stainless steels (representative steel types are 13Cr stainless steels such as SUS410 of the Japanese Industrial Standards), and precipitation hardening stainless steels (representative steel types are SUS630 and SUS631 of the Japanese Industrial Standards) are magnetic materials. It is preferable that all of the multiple pins 181b are made of the same material, but this is not a limitation.

[0014] One end of the pin 181b is threaded, and a screw hole is formed in the circumferential surface of the cylinder 181a. The end of the pin 181b is screwed into the screw hole, thereby fixing the pin 181b to the cylinder 181a. Preferably, an adhesive is used to prevent the fixation from coming loose. Although the pin 181b is firmly fixed to the cylinder 181a, it is better to take measures against the possibility that it may fall off during use. One such measure is to use a magnetic metal for the pins. Even if the pins are dropped from the cylinder during the production of CF-SMC and get mixed in with the fiber mat, they can be easily found using a magnetic metal detector.

[0015] The pins 181b extend perpendicular to the rotation axis of the first pin roll 181 and have, for example, a cylindrical shape, but are not limited to this. The boundary between the end face and the peripheral surface of the pins 181b may be chamfered. In other examples, as shown in Figures 4(a) to 4(e), the shape of the pins 181b may be a plate, a polygonal column, a cone, a truncated cone, or a truncated pyramid, or may be branched as shown in Figure 4(f). The diameter of the pin 181b is not limited, but may be, for example, 1 mm to 5 mm. The length of the pin 181b, that is, the distance from the tip to the base of the pin, is not limited, but may be, for example, 10 mm to 100 mm. It is preferable that all of the pins 181b have the same shape and dimensions.

[0016] It is preferable that the pins 181b are arranged periodically on the circumferential surface of the cylinder 181a in both the axial and circumferential directions.

[0017] In this specification, the maximum radius of the pin roll is defined as the distance from the rotation axis to the tip of the pin. In the first pin roll 181, the radius of the cylinder 181a is preferably half or more of the maximum radius of the first pin roll 181, and more preferably 75% or more. This is because the higher the ratio of the cylinder radius to the maximum radius of the pin roll, the smaller the difference in peripheral speed between the tip of the pin and the base of the pin when the pin roll is rotating.

[0018] Everything stated above regarding the first pin roll 181 also applies to the second pin roll 182 . Without being limited thereto, in order to reduce the costs of designing, manufacturing and maintaining the pin roller apparatus 180, it is preferable to match the designs and specifications of the first pin roll 181 and the second pin roll 182 in as many aspects as possible, including axial length, maximum radius, cylinder diameter, pin shape, dimensions, number and arrangement, and cylinder and pin materials.

[0019] As illustrated in FIG. 5, the maximum radius r of the first pin roll 181 M1 and the maximum radius r of the second pin roll 182 M2 and the distance between the rotation axes d 12 The difference between M1 +r M2 )-d 12} is preferably a positive value, but is not limited thereto. M1 +r M2 )-d 12} may be zero or a negative value, and if it is a negative value, it is preferably -10 mm or more.

[0020] Both the first pin roll 181 and the second pin roll 182 are rotationally driven by a drive mechanism (not shown). Rotating both the first pin roll 181 and the second pin roll 182 is advantageous in preventing the short carbon fiber bundle 20 from being clogged between these two pin rolls. The rotation direction and rotation speed of the first pin roll 181 and the second pin roll 182 may be independently controllable. 2, the first pin roll 181 is rotated so that the pins 181b move from top to bottom on the side facing the second pin roll 182, and the second pin roll 182 is rotated so that the pins 182b move from top to bottom on the side facing the first pin roll 181. This is because, when rotated in this manner, a strong shear force is unlikely to be applied to the short carbon fiber bundle passing between the two pin rolls. A strong shear force causes the carbon fiber bundle to become frayed and reduces the straightness of the carbon fiber bundle. In order to more effectively achieve this objective, it is preferable to make the peripheral speeds at the tips of the pins of the first pin roll 181 and the second pin roll 182 equal.

[0021] In the pin roller device, it is not essential to arrange two pin rolls side by side. The number of pin rolls provided in the pin roller device is not limited to two, and may be one, or may be three or more.

[0022] The magnetic sensor type metal detector 150 includes a magnetizer and a magnetic sensor. This type of metal detector is not affected by carbon fiber, which is conductive but not magnetic, and is therefore suitable for inspecting CF-SMC, which contains a large amount of carbon fiber, for metallic foreign bodies. If the pins of the pin roll are made of a magnetic metal, when the pins fall off and become mixed into the CF-SMC, they can be reliably detected by this type of metal detector. Even if the pin is made of SUS304, a non-magnetic stainless steel, if part of the structure has changed from austenite to martensite due to stress received after manufacture, it cannot be said that it will not be possible for it to be detected by a magnetic metal detector, but this is not certain. Therefore, a pin that is manufactured from a non-magnetic metal such as SUS304 and then becomes partially magnetic due to stress is not included in the category of "pins made from a magnetic metal."

[0023] The procedure for manufacturing CF-SMC using the SMC manufacturing apparatus 100 will be described below. First, a continuous carbon fiber bundle 10 is drawn from a previously prepared fiber package and fed to a chopper 160 . The number of filaments per bundle of the continuous carbon fiber bundle 10 is not limited, but is, for example, 3000 to 100000. The continuous carbon fiber bundle may be partially split in advance into a plurality of sub-bundles.

[0024] The continuous carbon fiber bundle 10 is cut by a chopper 160 into short carbon fiber bundles 20 . The fiber length of the short carbon fiber bundle 20 is, for example, within a range of 10 to 60 mm, and can typically be 0.5 inches (about 1.3 cm), 1 inch (about 2.5 cm), 2 inches (about 5.1 cm), etc., but is not limited thereto.

[0025] The short carbon fiber bundles 20 are guided through a shooter 170 to a pin roller device 180, dispersed by rotating first pin roll 181 and second pin roll 182, and then fall and accumulate on a first carrier film 41 to form a carbon fiber mat 30. In a pin roller device, an advantage of rotating two pin rolls so that the pins move from top to bottom on the side facing the other pin roll is that the carbon fiber mat is less likely to have a front and back surface, even if there is a weight distribution in the short carbon fiber bundles. The reason why the carbon fiber mat is unlikely to have a two-sided surface is because both the heavy short carbon fiber bundles and the light short carbon fiber bundles pass through the gap between the two pin rolls and fall onto the first carrier film. In other words, the position where the heavy short carbon fiber bundles fall and the position where the light short carbon fiber bundles fall are unlikely to be shifted along the transport direction of the first carrier film.

[0026] In a modified example, instead of using a chopper 160 to cut the continuous carbon fiber bundle 10 on-site to produce short carbon fiber bundles 20, short carbon fiber bundles that have been produced in advance in a separate process can be supplied to the pin roller device 180 through a chute 170.

[0027] Before the carbon fiber mat 30 is deposited, a first resin paste 51 is applied to the first carrier film 41 that is unwound from a roll, using a first coater 110 . The first resin paste 51 is a thermosetting resin composition, and its base resin is, but is not limited to, for example, vinyl ester resin (also called epoxy acrylate resin), unsaturated polyester resin, epoxy resin, polyimide resin, maleimide resin, or phenol resin. A mixed resin of vinyl ester resin and unsaturated polyester resin may be used as the base resin. The first resin paste 51 may contain, as necessary, a hardener, a polymerization inhibitor, a thickener, a reactive diluent, a low shrinkage agent, a flame retardant, an antibacterial agent, and the like.

[0028] In a separate process, a second resin paste 52 having the same composition as the first resin paste 51 is applied onto the second carrier film 42 using a second coater 120 . The second carrier film 42 is superimposed on the first carrier film 41 having the carbon fiber mat 30 placed on its upper surface, with the side on which the second resin paste layer 52L is formed facing down, and the laminate 60 thus formed is pressurized by the impregnation machine 140, whereby the carbon fiber mat 30 is impregnated with the first resin paste 51 and the second resin paste 52 to form a resin-impregnated carbon fiber mat.

[0029] The resin-impregnated carbon fiber mat is inspected for the presence of metallic foreign matter by a magnetic sensor type metal detector 150, and then wound onto a bobbin. Any part found to contain metallic foreign matter is either cut off on the spot so that it will not be wound onto a bobbin, or is marked so that it can be cut off in a later process. The resin-impregnated carbon fiber mat wound onto a bobbin is thickened as necessary and then shipped as CF-SMC.

[0030] CF-SMC is used to mold CFRP (carbon fiber reinforced plastic) products, for example, by compression molding. CFRP products that can be manufactured using CF-SMC are diverse, including parts for aircraft, automobiles, ships, and other types of transportation equipment, as well as sporting goods and leisure goods.

[0031] Although the present invention has been described above with reference to specific embodiments, each embodiment is presented as an example and does not limit the scope of the present invention. Each embodiment described in this specification can be modified in various ways without departing from the spirit of the invention, and can be combined with features described in other embodiments within the scope of feasibility. [Explanation of symbols]

[0032] 10 Continuous carbon fiber bundle 20 Short carbon fiber bundle 30 Carbon Fiber Matte 41 Daiichi Carrier Film 42 Second Carrier Film 51 First Resin Paste 51L First resin paste layer 52 Second resin paste 52L Second resin paste layer 60 Laminate 100 SMC manufacturing equipment 110 First Coating Machine 120 Second Coating Machine 130 Fiber mat depositing device 140 Impregnation machine 150 Magnetic sensor metal detector 160 Chopper 161 Cutter Roll 162 Receiving roll (rubber roll) 163 Guide Roll 170 Shooter 180 Pin roller device 181 First Pinroll 181b Pin 182 Second Pinroll 182b Pin

Claims

1. A method for producing a sheet molding compound, comprising: (i) dropping short carbon fiber bundles onto a moving carrier film while dispersing them with a pin roller device, and depositing a carbon fiber mat on the carrier film; (ii) impregnating the carbon fiber mat with a thermosetting resin composition to obtain a resin-impregnated carbon fiber mat; and (iii) inspecting the resin-impregnated carbon fiber mat for the presence or absence of metallic foreign matter with a magnetic sensor-type metal detector, wherein the pin roller device is provided with a rotatably driven pin roll, the pin roll comprising a cylinder and a plurality of pins arranged on its circumferential surface, and the plurality of pins are made of a magnetic metal.

2. The method according to claim 1 , further comprising cutting the continuous carbon fiber bundle into the short carbon fiber bundles by a chopper installed above the pin roller device.

3. The manufacturing method according to claim 1 or 2, wherein the pin roller device includes a first pin roll and a second pin roll arranged side by side as the pin rolls.

4. The manufacturing method according to claim 3, wherein the first pin roll is rotationally driven so that the pins move from top to bottom on the side facing the second pin roll, and the second pin roll is rotationally driven so that the pins move from top to bottom on the side facing the first pin roll.

5. The manufacturing method according to claim 3 or 4, wherein the sum of the maximum radius of the first pin roll and the maximum radius of the second pin roll is greater than the distance between the rotation axes of the first pin roll and the second pin roll.

6. The manufacturing method according to any one of claims 3 to 5, wherein the radius of the cylinder of each of the first pin roll and the second pin roll is equal to or greater than half of the maximum radius.

7. The manufacturing method according to any one of claims 3 to 6, wherein the peripheral speed at the tip of the pin of the first pin roll is equal to the peripheral speed at the tip of the pin of the second pin roll.

8. An apparatus for producing a sheet molding compound, comprising: a fiber mat depositing apparatus having a pin roller apparatus; and a magnetic sensor type metal detector, The pin roller device is a sheet molding compound manufacturing apparatus comprising a rotationally driven pin roll, the pin roll consisting of a cylinder and a plurality of pins arranged on its circumferential surface, the plurality of pins being made of a magnetic metal.

9. A sheet molding compound manufacturing apparatus as described in Claim 8, wherein the pin roller device includes a first pin roll and a second pin roll arranged side by side as the pin rolls.

10. 10. The sheet molding compound manufacturing apparatus of claim 9, wherein the sum of the maximum radius of the first pin roll and the maximum radius of the second pin roll is greater than the distance between the rotation axes of the first pin roll and the second pin roll.

11. 11. The sheet molding compound manufacturing apparatus of claim 9 or 10, wherein the radius of the cylinder of each of the first pin roll and the second pin roll is equal to or greater than half of the maximum radius.

12. The sheet molding compound manufacturing apparatus of claim 8, wherein the fiber mat deposition device has a chopper positioned above the pin roller device.

13. 9. The sheet molding compound manufacturing apparatus of claim 8, further comprising two coaters and an impregnator.

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